help with Hour meter inop

schmalts · Jul 1, 2004

I just sold my jinma and the guy said the hour meter stopped working but the tach runs yet. I dont have a manual or trust the wireing diagram anyway but here goes. What powers the hour meter? is it tied into the oil pressure switch ,or internally powered when it gets a tach signal?
I know its not the key only because i left that on several times without racking up hours.
I gave it a good bath just befor i sold it and wonder if a wire or internal got corroded.
Its a JM284 w/standard guages. not the upgrade guage cluster.

SPIKER · Jul 1, 2004

hey schmalst:

I'm not sure, but I think they only time when above about 1500 PRM. so I think maybe from the signal generator??? not 100% sure though as we have similar aged 284's mi9ne acrues but not when ideling or setting with key on. some where about 1500 mine starts so I htink I have more actual hrs than it shows buy about 100hrs probably from ideling time and such. I got stuck on phone for 45 min after refueling left it idel after mowing., time didn't change. mow time dies tick her up though at rate that seems to be some place in that RPM range.

Mark M /forums/images/graemlins/confused.gif

greg_g · Jul 1, 2004

If standard gauges means the hour meter is a round gauge all by itself, then the two wires are:
#26 ground side (from OPSU)
#25 supply side (12v common)

//greg//

Travis_R · Jul 1, 2004

Not for sure, but do you think it could be a BLOWN FUSE? /forums/images/graemlins/blush.gif

Travis R

greg_g · Jul 1, 2004

(
Not for sure, but do you think it could be a BLOWN FUSE?)
Wire #25 delivers 12v from the fuse box to all the gauges Travis. If it was a fuse, none of them would work.

//greg//

Soundguy · Jul 2, 2004

Is it -not- a mechanical gauge? I'm not at all familiar with the jinma gauges.. but for instance on my ford.. the hourmeter racks up hours.. but the hours are also based on 'pto' rpm. Therefore.. if you are running at half pto rpm.. then you only rack up 1 hour for every 2 hours runtime.. etc...

Soundguy

schmalts · Jul 2, 2004

It has power because the tach works. Need to find out what triggers the hour meter to work.
If I cant get it going for him i will get him a new one. Anyone have a spare they want to sell or trade for a starter motor?
It fogged up pretty good when i degreases and sprayed off the top of the fuel tank so i may have got a lot of moisture in it. The tach didnt work for a day but after a drying period it started up again.

greg_g · Jul 2, 2004

( It has power because the tach works. Need to find out what triggers the hour meter to work. )
Like I said, oil pressure. From the perspective of an electrical circuit, the OPSU is actually the meter ground. Wire #26 connects to ground - WHEN the OPSU delivers it. No oil pressure, no ground. Once the engine is started, oil pressure pushes against a diaphram. As soon as there is enough pressure, the diaphram makes a connection to ground. At this point, 12v from wire #25 can finally make a complete circuit; through the meter to ground.

But in your case, it sounds like it's no longer (or intermittently) not even making it through the meter anymore. This Google search should get you started on the road to a replacement.

//greg//

bluechip · Jul 2, 2004

On the older units, those before tachs became standard, the then separate hour meter was triggered by oil pressure, but not anymore. To be honest, I have not paid a lot of attention to the hour meter as it relates to engine speed compared to clock time. I'm guessing Schmalts' buyer has run it long enough to notice that the hour meter is not working, so it is probably not changing at all at any engine speed. I was test running a KAMA the other day and noticed that at low RPM the hour meter seemed to rack up time slower and at higher RPM faster. Greg have you noticed this on yours? Even though the KAMA has the combined panel, they probably use a similar tach. I always figured the mechanical tachs would have to count hours by revolutions but it may be that the electronic tachs duplicate that method.

greg_g · Jul 2, 2004

( On the older units, those before tachs became standard, the then separate hour meter was triggered by oil pressure, but not anymore.)
Which is why I specified right up front that this Wire #25/26 information applied only to the older units with a separate round hour meter.

( noticed that at low RPM the hour meter seemed to rack up time slower and at higher RPM faster. Greg have you noticed this on yours? )
Can't help on this one Chip. The tenths counter on mine has a big chunk missing. I'd have to guess what it's saying, and timing the hour counter would be a waste of fuel.

//greg//